Hollow charges known as "first generation" charges and developed during the 1950 decade, made use of a copper covering in the form of a "tulip" or having a "double slope", its thickness generally progressively increasing.
Priming took place at a central point and developed an arcuate wave. The explosive, usually hexolite, had a hexogen content of approximately 60%, obtained by decantation, and the charge was less concentrated towards the rear. This type of hollow charge represented an enormous advance compared with the previous materials (period 1938-1945). The penetrating power was thus increased from 0.5/1 calibre to 4 calibres.
The second generation (the 1960 decade) was directed towards conical coverings, still made of copper, having an angle of approximately 60.degree.. The same explosive was used, but improved methods of charging enabled the hexogen content to be increased to more than 70%, its concentration being almost uniform from the base of the covering to the priming means.
An important feature of this second generation of hollow charges was the move towards finding means comprising a screen and producing a toroidal wave. The penetrating power then increased considerably once more and went from 4 to 5 calibres, or a little more than 5 calibres.
It is now required to effect a further advance, in particular by improving the effectiveness of the hollow charge against modern composite armour-plating which has a very considerable thickness whatever its composition and the nature of the various heterogenous layers that form each type of composite armour-plating. In this connection, any extension of the jet effect or other effect of the hollow charge can result in an increase in the end-effect.
The following French patents in the name of the present applicant represent new and important advances as regards the end-effect:
______________________________________ Pat. No. 75 14 091, of 6th May 1975 "Double hollow Pat. No. 77 35 320, of 24th November 1977 charge" and Pat. No. 76 28 964, of 27th September 1976 "Charge consisting of coaxial annular layers" ______________________________________
These are concerned in particular with improved methods of charging, on the one hand, and the structure or arrangement of the charge, on the other.